This study aims to investigate the acute effects of Tribulus terrestris supplementation on anaerobic performance and sprint times in trained male combat sport athletes. A total of 28 athletes from kickboxing, Muay Thai, and taekwondo disciplines will participate in a randomized, double-blind, placebo-controlled, crossover trial.

Participants will ingest either a single oral dose of 625 mg Tribulus terrestris (40% saponins) or a placebo 60 minutes before performing performance tests. The performance assessments will include a 30-second Wingate anaerobic cycling test and 20 m and 100 m sprint tests using photocell timing gates. After a wash-out period, participants will cross over to the alternate condition.

The primary outcomes are peak power and mean power from the Wingate test and sprint times over 20 m and 100 m.

This trial is designed to evaluate the acute ergogenic potential of Tribulus terrestris supplementation in combat sport athletes. Tribulus terrestris has traditionally been marketed as a natural testosterone booster and performance enhancer, yet its acute effects on high-intensity exercise performance remain unclear.

Design and Methods

Participants: 28 trained male athletes (Kickboxing n=12, Muay Thai n=10, Taekwondo n=6), aged 18-30 years, with at least 2 years of competitive training experience.

Design: Randomized, double-blind, placebo-controlled, crossover.

Intervention: A single dose of 625 mg Tribulus terrestris (40% saponins) or matched placebo (cellulose). Supplements will be ingested 60 minutes before testing.

Procedures: After a standardized warm-up, participants will complete a 30-second Wingate test on a Monark cycle ergometer (resistance = 10% body mass) to measure peak power, mean power, and fatigue index. Following 10 minutes of recovery, participants will perform 20 m and 100 m sprint tests using double-beam photocells (Witty timing system). Each participant will perform both supplementation conditions with a ≥72 h wash-out.

Outcomes Primary outcomes: Wingate peak power (W, W/kg), mean power (W, W/kg). Secondary outcomes: 20 m and 100 m sprint times (s).

Ethics: Approved by the Ethics Committee of Atatürk University (Protocol No: E-70400699-000-2500104927). Written informed consent will be obtained from all participants.

Inclusion Criteria:

• Male athletes aged 18-30 years
• Engaged in combat sports (kickboxing, Muay Thai, or taekwondo)
• Minimum 2 years of continuous training experience
• Training at least 4 sessions per week
• Free from injury or illness at the time of testing
• Provided written informed consent

Exclusion Criteria:

• Use of ergogenic supplements, anabolic steroids, or hormonal treatments within the past 3 months
• Consumption of caffeine, alcohol, or performance-enhancing substances within 24 hours before testing
• Current musculoskeletal injury or medical condition that may limit performance
• Any chronic disease or contraindication to high-intensity exercise

Plan Description: If shared, the de-identified individual participant data (IPD) will include Wingate anaerobic test outcomes and sprint performance times. These data represent the analyzable dataset collected during the study. If data are not shared, this will be due to limitations related to participant confidentiality and data protection.

Access Criteria: Data may be made available upon reasonable request from qualified researchers for academic, non-commercial purposes. Requests will be reviewed by the study investigators, and data will only be shared after publication of the primary results.

Participants, investigators, care providers, and outcome assessors were blinded to group allocation. Supplements were prepared in identical capsules to ensure blinding integrity.